Staple and method of making the



June 20, 1944. GREENWOOD I 2,351,608

STAPLE AND METHOD OF MAKING THE SAME Filed Jan. 18, 1941 s Sheets-Sheet1 Invert ?or',

June 20, 1944. T. T. GREENWOOD 2,351,608

STAPLE AND METHOD 0F MAKING THE SAME Filed Jan. 18, 1941 3 Sheets-Sheet2 I K w z M3 w .w

June 20, 1944. T. T. GREENWOOD T ,3

I STAPLE AND METHOD OF MAKING THE I Filed Jan. 18, 1941 s Sheets-Sheet sIf M,

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Patented June 20, 1944 UNITED STATES PATENT OFFICE Talma T. Greenwood,Boston, Mass, assignor to Superior Manufacturing Company, Fitchburg,Mass, a corporation of Massachusetts Application January 18, 1941,Serial No. 375,032

Claims.

This invention relates to staples and particularly to the type of stapleemployed for securing a wire, and particularly an electric conductor, toa support; and has to do with a construction of staple and a method ofmaking the staple, so that the staple can be driven into hard materialswithout bending or spreading of the legs.

The staple with which the present invention is particularly concerned ismade of wire, usually flattened so that the wire is wider than it isthick, and having two spaced parallel legs pointed at their similar endsand integrally connected at their other ends by a connecting member orsocalled bridge. The bridge of the ordinary staple is arched so that themiddle thereof upstands above the ends of the staple legs, although theheight of the arch may be different for difierent staples.

Such a staple is insulated by an insulating strip or saddle which islocated between the upper parts of the legs under the bridge and isformed to provide an insulating channel for an electric conductor.

In at least one make of staple, an attempt is made to bend the staplewire to have the bridge flat or at right angles with the legs but thebridge, nevertheless, is slightly arched or is higher in the middle thanat the ends.

It is quite diflicult to drive this arched type of staple intoa hardsupport, as into a hardboard, especially by an inexperienced person,without bending the staple legs in the plane occupied by the legs. Thisbending action of the usual staple construction as above described whendriven by the usual hammer into a sufliciently hard material isinevitable.

The hammer strikes the bridge of the staple. Since the bridge is archedthe hammer head strikes the middle of the bridge. lC'he blow of thehammer thus has a relatively large component acting at right angles tothe legs and a relatively small component acting in the direction of thelegs. When the wire of which the staple is made is suflicientlyresistant and the resistance of the material to penetration by the legsis sufiiciently small the staple can be driven home without bending.When, however, the resistance of the material to penetration issufficiently high and the staple wire is of relatively small gauge, asis particularly the case with insulated or saddle staples, the bridgeflattens and hence spreads apart the upper ends of the legs of thestaple. On following blows the upper part of one leg of the staple isbent inwardly and the other leg of the staple is pushed outwardly by thethrust of the bridge and also has its upper end part bent inwardly sothat the staple is deformed and cannot be driven further, will not holda wire securely and looks unsightly.

An attempt has been made to prevent such bending action of the stapleand thus to improve its driving ability by lowering or indenting themiddle part of the staple so that the bridge has a central indented ordepressed part between two elevated bent parts located between the legsof the staple. Such a, staple under some conditions has a somewhatbetter driving quality than the regular staple but is greatly inferiorin its driving quality to the staple that is the subject of the presentinvention. It does not appear that such a staple is on the market at thepresent time.

To produce a staple that will not bend when driven into a hard orresistant surface, I have discovered that it is not suiiicient merely todepress the middle part of the bridge of the staple. I have discoveredthat the striking point or head of the staple, that is, the point hit bythe hammer, must be so close to the line of the leg of the staple thatthe leg will not bend under the hammer blow. For best results, thisstriking point should be in the axial line of the leg. I have producedsuch staples which have excellent driving qualities. It is notessential, however that the striking point be precisely in the axialline of the leg, and, where the staple wire is sufficiently stiff, thestriking point can be somewhat at one side of the axial line. Thestriking point, however, should be as close in line with the leg as itis practicable to make it. A staple so constructed constitutes an objectof the present invention.

I have found further that the best results are obtained when the bridgeis in the form of an inverted arch which extends between the legs in acontinuous curve of one character and where the ends of the arch jointhe material of the legs abruptly. I have further found that the pointof connection between the inverted arch and the leg of the staple on theunder side of the arch, for best results, should be abrupt and shouldnot be a curve of large radius as one approximating the thickness of thewire. Such a staple constitutes an object of the present invention.

I have also found that the driving quality of the staple is improved ifinstead of merely bending the staple wire to form the inverted bridgethe material of the bridge at least in part is compacted by impact ofthe forming die, thereby making the bridge more resistant to bendingthan it would otherwise be. This construction is also an object of thepresent invention.

A further object of the invention is an improved method of making thestaple.

Another object is generally to improve the resistance of the staple tobending when subjected to driving impacts.

Fg. 1 is a perspective view of one form of staple embodying the presentinvention.

2 is a front elevation of the staple of Fig. 1 having an insulatingsaddle thereon.

3 is a sectional view taken along line 3-3 of Fig. 2, and illustratingthe shape of the staple making wire.

Fig. 4 is an enlarged front view of the bridge end of the staple ofFigs. 1 and 2.

Fig. 5 is an enlarged view of the staple forming dies in position toform a staple.

Fig. 6 is a view of the dies of 5 with the staple formed but prior tothe bridge shaping process.

Fig. 7 is a view showing the completion of the bridge shaping process.

Fig. 8 is an enlarged detail of the upper end of a staple made inaccordance with a somewhat different method.

Fig. 9 is an enlarged detail of the upper end of the staple showingupright and inverted bridges having the same length.

Figs. 10 and 11 are views similar to Figs. 6 and 7, showing theformation of the staple of Fig. 8.

Fig. 12 is a view of a modified form of dies for making a staple inaccordance with the present invention.

The staple with which the present invention is particularly concerned,and one form of which is illustrated in Figs. 1 through l, comprises theparallel legs and 22, the lower ends of which. are cut diagonally from alength of staple making wire to provide oppositely inclined faces 24 andpointed ends 26. The upper parts of the legs integrally connected bybridge The staple is made from initially round wire which has beenflattened to provide the opposite flat sides 39 and the rounded edges asillustrated in Fig. The staple is formed by bending the wire across theflat faces so that the staple leg is wider transversely of the plane ofthe legs than the leg is thick.

When the staple is used for securing an electric conductor to a support,as to a wood board, the staple is provided with a saddle '34 crmipris ofa strip of insulating material. as :(ibre, throi vb parts of which thelegs of the staple with the bridge overlying the saddle, the saddlehaving a channel which receives the conductor. the walls of the channelproviding insulation between. the conductor and the legs of the stapleand the bridge, a staple for use with such insulating saddleconstituting an important feature of this invention.

The staple embodying the present invention can be made by the diesillustrated diagrammatically in Fig. 5. The initially straight 5.33.1319mak ing wire 38 rests upon the top face of a stationary anvil 49, whichface for making the common staple is flat. Said anvil is located betweena pair of side wipers or forming dies 42. These dies are moveddownwardly and bend the wire about the anvil causing the bridge formingpart of the wire overlying the top face of the anvil. to arch upwardly.as indicated at M, Fig. 6. A hammer or striking member 453 locatedbetween the forming dies 42 and at the lower part of the stroke of theforming dies the hammer is forced downwardly onto the bridge.

In the manufacture of my improved staple, in the form illustrated inFig. 4, the anvil 48 is given a concave upper face 48 which preferablyextcndi entirely to the side faces of the anvil. The lower face of thehammer 46 is made convex, as at i" With this construction, the hammer 46depresses the arched bridge 4-1 of the staple into the concave face d3of the anvil and thus depresses the bridge or inverts the arch in themanner illustrated in Figs. l and 7, the length of the chord of theconcave arch of the upper face of the bridge being approximately equalor not materially less than the distance between the confronting facesof the legs. This construction provides the staple with a pair ofstriking points or heads located close to the line of the staple legs,All parts of the bridge between these striking points are below a planeperpendicular to the legs and passing through the points so that thehead of the hammer can engage only the points and not the bridge. Thepoints are so close to the line of the staple legs that the staple canbe driven. into hard wood or the equivalent without the bending of thelegs. Each striking point may be struck independently of the otherwithout bending either leg. The striking points 52 can be positionedimmediately above the legs, as indicated by the striking points 54 ofthe staple of Fig. 8, by a proper selection of the radius of the curveEli of the striking face of the hammer 45 and by the length of materialin the bridge lid, 6, prior to the shaping of the bridge by the hammer.Ordinarily, however, it is not necessary to position the striking pointsentirely within the out-- lines of the legs.

In forming my improved staple, the curve of the striking face of thehammer 46 is more important than the curve of the top face 48 of theanvil. The curve of the face 5i] in large part determines the positionsof the striking points 52 with respect to the legs of the staple, whilethe concave face 48 of the anvil mainly provides a space into which thematerial of the bridge can be depressed. The amount of depression of themiddle part of the bridge below the plane including the striking points52 is not particularly important, providing the staple is properly madein the first instance, so long as the body of the bridge remains belowthis plane during the driving of the staple and the consequent possiblesmall deformation of the surfaces of the striking points under thehammer blows. It is important that the bend 5E between the staple legand the bridge be as sharp as it is practicable to obtain as thispermits the striking points to be set back within or close to theoutline of the legs. in forming (lies as illustrated in Figs. 5 and 6,by a simple bending of the material of the bridge without impacting thematerial, although I have found it frequently desirable to impact thebridge material to make the material denser and the bridge stiffer thanin the ordinary staple as it is customarily made. The sharp bend 58requires the anvil to have sharp edges 58, Fig. 5, which is desirable inthe Fig. 5 dies in that the edges engage the initially upwardly archedbridge and hold the staple from moving downwardly with the side wipersduring the time that the bridge is being inverted and shaped by thehammer 46.

The amount of arch in the bridge after the staple legs have been bentand before the bridge has been inverted by the hammer 46 control theamount that the arch of the bridge can be inverted or depressed withoutstretching the bridge material. Fig. 9 illustrates this situation Wherethe arch 60, illustrated in dotted lines, represents the bridge prior toits inversion into the form embodying the present invention andillustrated at 62. In both cases the medial length of the bridge is thesame. The striking points of the staple are at 64 in line with the innerface of the leg and the staple can be driven into very hard materialswithout the bending of the legs. The inverted bridge 62 thus is formedWithout any stretching of the brid material other than that which takesplace at the outer face portions of the curves. It is understood that ifthe depression is too great the bridge material will stretch and thestriking points will be pulled inwardly of the legs so that theresistance of the staple to bending is reduced.

By a proper shaping of the striking face of the anvil, the material canbe swedged into the dotted positions indicated at 56 to set the strikingpoints 68 back within the outline of the staple legs and into the axialline thereof.

The staple of the present invention also can wipers 14 move downwardlyon opposite sides of the anvil to bend the legs and form the archedbridge as before. When, however, the staple legs have been completelyformed and the dies 14 overlie approximately the entire length of theleg, the dies are then caused to be stationary and are moved inwardlyand clamped against the staple, thereby holding the staple againstmovement longitudinally thereof during the bridge shaping operation.This can be done in a side action press or in any convenient manner notnecessary to illustrate herein.

After the staple is clamped stationary the striker or hammer "it withthe curved striking face 78 is brought into engagement with the archedbridge of the staple and forces it downwardly towards the anvil untilthe inner face of the middle part of the bridge engages the top plateface of the anvil. This action causes the arch of the bridge to flattenand ultimatelyto assume the configurat on of the striking face 18 of thehammer. as illustrated at 89, the under surface of the bridge alsoassuming a correspondingly curved shape. Since the staple is held fromlongitudinal movement during the bridge forming operation and since thelength of the arch is greater than the direct distance between theconfronting faces of the legs the endwise thrust of the bridge on theends thereof as the bridge is being straightened causes the bend 82between the bridge and the end of the arch first to straighten and thento bend at a sharp angle, as illustrated at 84, Fig. 11, the outer curve85 being also made sharper as at 88. The excess length of the bridgecauses the bridge to reshape itself endwise to provide a sharp radius ofbend at 88 and striking points or heads 90 which are within or close tothe outline of the leg. By varying the amount of material in the archprior to the inversion of the arch, the position of the striking points90 may be controlled and located where desired. It is possible to foldthe bridge fiat against the inner face of the staple leg by having asufficiently high arch prior to the bridge shaping action.

In forming the usual staple, there is a tendency sometimes for thepointed ends of the legs to diverge after the staple is removed frombetween the dies and to prevent this divergence and to insure parallellegs the staple wire is bent abruptly over the anvil by having butlittle relief at the confronting corners of the forming members 42. Withthe present construction of staple, due to the inversion of the bridge,the ends of the bridge tend to be forced apart or outwardly and hencetend to swing the pointed ends of the legs inwardly or toward each otherand against the anvil. Thus, the legs are brought into parallelismwithout difficulty and without having to bend the wire sharply over theanvil. The confronting corners of the side wipers or forming members 42can thus have great relief as indicated at 92, Fig. 5, so that thebottoms of the wipers first engage the simple wire remote from theanviland thus cause the wire to bend over the anvil to form a highbridge.

Fig. 5 also represents, at the right in .the figure, coacting shearelements for cutting a staple length of wire from a longer wire, andsimultaneously forming beveled or tapered driving points on both severedends. The dotted line represents the rear edge of the shear element onthe forming member 42 for coacting with the relatively stationary shearelement shown below the wire at the right in Fig. 2.

While I prefer to form my staple over an anvil having a concave facethat merges with the flat opposite faces, as in Fig. 5, or where theanvil has a flat upper face, as in Fig. 10, the upper face of the anvilcan be otherwise constructed, as for instance, in Fig. 12. In thisfigure, the anvil 94 has thin upstanding ribs 96 that are on oppositesides of an inverted channel 98 in which a part of the bridge materialis depressed. This anvil produces a satisfactory staple, especiallywhere the staple has a high arch prior to the inversion and the legs ofthe staple are clamped against the anvil so that the staple does notmove downwardly when the bridge is shaped. The hammer We in thisinstance can be in the form of a relatively thin bar having a slightlyrounded lower face so as not to cut the bridge material. The hammermoves downwardly against the arched bridge and forces the ends of thebridge outwardly and upwardly so as to pr0- duce a sharp bend at thejunction between the bridge and the leg with elevated striking pointsthat are close to or entirely within the outline of the leg. The bridgebends up over the rib at of the anvil so that the rib, with properdimensions thereof, does not receive any particular pressure thereon butmerely serves to locate the arch of the staple at the time the staple isclamped against the anvil. There is no particular advantage to beemployed in using this type of anvil over the fiat faced anvil of Fig.10 or the concave-faced anvil of Fig. 6, and the construction asillustrated is shown to illustrate that a considerable variation ofanvil and hammer configuration can be employed to produce a highlysatisfactory staple.

From the above description it is apparent that the staple of the presentinvention has two striking points or heads; that the bridge is depressedbelow these points; and that the striking p nts are so close to the legsof the staple that owner part of the staple leg wi l not bend or curlover when the adjacent striking point is hit by the hammer. It is notsufficient merely to have the striking point close to the line of thestaple lc- The material between the vertical tie striking point must soresistant mation that it will not bend when the striking point is hit.This is accomplished by hav sharp a bond as possible at the junction ofthe bridge and the leg, this junction making something less than a rightangle. If the junction "radual, as by being a curve or a right angle,where the line of impact on the striking point outside the out of theleg, the relatively gradual curvature thus produced between the strikingpoint and the leg permits the materia to bend easily under impact.

In accoi, s with the construction herein de sci-i d, no of junctionbetween the bridge and the leg s abrupt and hence bending is not liableto to 0 place.

Fur rnim'e, the shape and condition of the 3 such that when one strikingpoint and the adjacent leg penetr the 1g surface, the other leg shouldnot be deformed. With the described construction, the inverted does notchange its shape or bri flatten when one striking point alone is hit andhence there is no tendency to force it e unstrucl: leg away from thestruck leg. hus, the two legs remain parallel with each other throughouttheir lengths regardless of whether one striking point or both strikingpoints are hit. It sometimes happens that a staple leg tends to move inan undesired rection when driven especially into g1 ll hardwood. Withthe present staple the direction of penetration of the legs can be thanerl by hitting one striking point or the other so that position of thestaple can be cor m and the staple can be driven more ac curately thanwith any other staple with which I am aware.

I claim:

1. The method of improving the driving quality of :1 st ,ole havingspaced legs connected by a bridge member integral with said legs, whichmethod. consists in providing the staple with two driving heads locatedabove all other parts of the staple and each so close to the line of aseparate leg that the resistance of a leg to bending under impact on ahead is more than its resistance to penetration of a penetrablesupporting material. by forcing the bridge member downwardly between thelegs and laterally toward the legs and causing the tops of the legs toupstand above the bridge member and provide the aforesaid drivinc heads.

The method of making a staple of improved drivin ability having parallellegs and a bridge ,7 a1 with and connecting said legs, which methodconsists in joining the ends of the bridge and legs abruptly at theinside of the legs by positioning the bridge below the ends of the legswhere they join the bridge and forcing bridge material laterally towardthe legs.

3. The method of making a staple of improved driving ability having legsconnected integrally at their one ends by a bridge member, which methodconsists in bending a straight staple wire into staple shape andproviding a bridge member that is upwardly arched between the legs, andthen inverting the arch in such manner that the convex side of the archfaces in the same directlon as the free ends of the legs and the ends ofthe arch abruptly join said one ends of the legs and said one ends standabove the body of the arch.

l. The method of makin a staple of improved driving ability having legsconnected integrally at their one ends by a bridge member, which methodconsists in bending a straight staple wire into staple shape andproviding a bridge member, and then forcing the body of the bridgemember below the said one ends of the legs to position said one endsabove th body of the bridge memher.

5. The method of making a staple of improved driving ability having legsconnected integrally at their one ends by a bridge member, which methodconsists in forming he staple with the body of the bridge member archedabove the legs, holding the staple against movement in the directions ofthe length of the legs, and forcing the body of the bridge memberinwardly of the legs and flattening the arch and forcing the ends of thebridge member outwardly toward the legs.

6. The method of making a staple of improved driving ability having legsconnected integrally at their one ends by a bridge member, which methodconsists in forming the staple with the body of the bridge member archedabove the legs, holding the staple against movement in the direction ofthe length of the legs, and forcing the body of the bridge memberinwardly of the legs and flattening the arch and forcing the ends of thebridge member outwardly toward the legs, and causing th bridge member toassume an inverted arco form the length of which is not materiallygreat-er than the initial length of the bridge member.

7. The method of making a staple of improved driving ability having legsconnected integrally t their one ends by a bridge member, which methodconsists in forming the staple with the body of the bridge member archedabove the legs, holding the staple against movement in the direction ofthe length of the legs, by confining the legs between rigid surfaces,and forcing the body of the bridge member toward the free ends of thelegs and the ends of the bridge member outwardly and against said rigidsurfaces and upwardly above the legs and providing striking heads closeto the line of the legs and elevated above the body of the bridgemember.

8. The method of making a staple of improved driving ability having legsconnected integrally their one ends by a bridge member, which methodconsists in forming the staple with the body of the bridge member archedabove the legs, holding the staple against movement in the directicn ofth length of the legs and forcing the body of the bridge member towardthe free ends of the legs and the ends of the bridge member outwardlyand upwardly above the legs and providing striking heads close to theline of the legs and elevated above the body of the bridge member.

9. A staple formed of a single length of wire bent into approximatelyU-shape providing two substantially parallel legs pointed at their oneends and connected integrally at their other ends by a bridge of lesserlength than a leg, the wire at the juncture of the bridge and the legsbeing abruptly bent inwardly of the legs providing driving headssubstantially over the and upstanding above the intervening parts of thebridge, the driving heads being close together and shaped and adapted tobe struck simultaneously by an ordinary hammer, each leg-point being ina line perpendicular to the driving plane of the heads and passingthrough the associated driving head, and the legs being substantiallyparallel to and lying in said lines.

10. A staple having two substantially parallel legs pointed at their oneends and connected integrally at their opposite ends by a bridge oflesser length than a leg, the staple at the bridge-end thereof havingdriving heads substantially over the legs and upstanding above theintervening parts of the bridge, the driving heads being close togetherand shaped and adapted to be struck simultaneously by an ordinaryhammer, each legpoint being in a line perpendicular to the driving planeof the heads and passing through the associated driving head, and thelegs being substantially parallel to and lying in said lines.

TALMA T. GREENWOOD.

